664 THE GENERATIVE ORGANS. 
female within the cloacal pouch or ovipositor, or are introduced 
into the orifice of the utero-vaginal tube. 
In the Cockroach there is no vestige of a penis, and the 
right and left gonapophyses are unsymmetrical. The left 
gonapophysis is provided with a long movable hook, but the 
right one contains a cavity protected by a spring lid, which 
closely resembles the organ on the palpus of male spiders. I 
have little doubt it serves to contain a large spermatophore, 
which is transferred by the hook to the cloacal pouch of the 
female. Cornelius,* who gives a description of the sexual act 
in this insect, describes it as being accomplished with great 
rapidity, and it is highly improbable that the sperm could be 
transferred directly from the short wide vas deferens of the 
male to the oviduct or receptaculum of the female. The 
probability that a large spermatophore is simply transferred to 
the cloacal pouch of the female is rendered greater by the fact 
that such is very generally the nature of the act of copulation 
in the Orthoptera. 
The Vas Deferens varies greatly in length in different insects ; 
it is sometimes wide and short, as in the Cockroach, some- 
times long, narrow and much convoluted. In the Blow-fly it 
is 1°5 mm. in length, and is thickest at its commencement, 
where it has a diameter of ‘2 mm., tapering gradually towards 
its termination, where its diameter is about "1 mm. It has the 
same structure as the paragonia and vasa efferentia. It termi- 
nates in the ejaculatory sac. 
Segmental Ducts——The vasa efferentia, paragonia and vas 
deferens are apparently morphologically related to segmental 
tubes. I shall, however, return to this subject. They are 
constantly present, and so offer a marked contrast to the 
remainder of the genital tube, the ejaculatory sac and duct, 
which I regard as the ‘secondary duct.’ This is developed 
from the hypodermis, and is frequently entirely wanting, as is 
apparently always the case when there is no intromittent penis, 
or when this organ is replaced by a pair of more or less complex 
gonapophyses. 
* ©Beitriige zur nahern Kenntniss der Periplaneta orientalis.’ Elberfeld. 1853. 
